TRANSCRIPTION

Question 1

Typed of RNA

Answer 1

tRNA- serves as and adapter for transcription
mRNA- contains the genetic code to be translated
rRNA- maschinery for synthesis
snRNA- ripening of premRNa
snoRNA- chemical modification of rRNA
miRNA- prevents translation
siRNA- degrades RNA molecules

Question 2

RNA Polymerase Versus DNA Polymerase

Answer 2

1. polymerase only works on one strand
2. own helicase activity
3. NO for need priming
4. RNA polymerase does NOT proofread product

Question 3

RNA polymerase - Prokaryotes

Answer 3

RNA polymerase “core” enzyme: två aplha, en beta, en beta prime

• Sigma factors are one component of the multicomponent RNA polymerase enzyme that allow the RNA polymerase to recognize the initiation (promoter) site.

Question 4

RNA polymerase holoenzyme:

Answer 4

aplha: Binds regulatory sequences
Beta :Forms phosphodiester bonds
beta prime: Binds DNA template

Question 5

Sigma factor

Answer 5

allow the RNA polymerase to recognize the initiation (promoter) site.

Question 6

Termination of Transcription in E. coli

Answer 6

Two types of terminator sequences occur in prokaryotes:
1. Type I (rho-independent)
Palindromic, inverse repeat forms a hairpin loop and destabilize the DNA-RNA hybrid.
Type II (Rho-dependent)
Involves rho factor proteins, believed to break the hydrogen bonds between the template DNA and RNA.

Question 7

Inhibitors of transcription

Answer 7

aplpha-amantin: RNA pol 2
Rifampicin: blocks promoter clerance
actinomycin-D: elongation

Question 8

Activation of chromatin

Answer 8

1. Acetylation

2. Remodelling

Question 9

cis-acting elements

Answer 9

DNA sequences close to a gene that are required for gene expression

1.Promoter:
a.Core promoter when to occur
in eukaryote: TATA-box, Initiator (Inr)
in prokaryote: -10 region, Inr

b.Proximal elements of promoter hoe frequent
in prokaryote: -35 region
in eukaryote: CAAT-box,(CTF) GC-box(sp1)
UPE: upstream promoter element
UAS: upstream activating sequence

2.terminator: signal to stop
transcription.

3.EnhacerA regulatory DNA sequence that greatly enhances the transcription of a gene

4. Silencer
   A DNA sequence that helps to reduce or shut off the expression of a nearby gene.

Question 10

Trans-acting factors

Answer 10

proteins, that bind to the cis-acting elements to control gene expression.

1)  RNA polymerase
               prokaryotic RNA Pol
               eukaryotic RNA Pol
(2)  Transcription factors
                Basal/general TFs
                Specific TFs
(3)  Domains of trans-acting factors
                DNA binding domain DBD
                transcription activating domain

Question 11

Eukaryotic RNA polymerase

Answer 11

RNA Polymease 1 (rRNA (28S,16S,5,8S)
RNA Polymerase2 (mRNA, snRNA, miRNA, lncRNA)
RNA Polymerase 3( tRNA, 5S RNA)
RNA Polymerase(mt)

Question 12

Finding promoter in Eukaryotes

Answer 12

reguire GTF

 - TFIIA,B,D,E,F,H
 - TFIID (TAF, TBP(14))

Question 13

CLOSED COMPLEX

Answer 13

RNAP binds to DNA with ist GTF

Question 14

OPen complex

Answer 14

Unwind DNA by TFIIH getsphosphorylated at CTD(carboxy terminus domain) by TFIIH

Question 15

Post transcriptional modification

Answer 15

5 cap
poly A tail
RNA edeting
splicing

Question 16

where does capping and poly A tailing occur

Answer 16

nuclei

Question 17

snRNA

Answer 17

U1,U2,U4,U5,U6

Question 18

SPLICOSOME

Answer 18

snRNA, SR, RRM

Question 19

protein U2AF

Answer 19

helps U2 snRNP to bind to the branchpoint

Question 20

Production of miRNA

Answer 20

dsRNA is cleaved by Dicer (protein) into multiple ±20 nucleotide long dsRNA. These are then incorporated into RISC complex (=RNA induced silencing complex) where 1 of the strands is degraded. siRNA are used for recognising and degrade an identical RNA from which it derives.

Question 21

hnRNA processing

Answer 21

equences of RNA that must be removed in a process which also joins together the appropriate coding segments to form the mature mRNA. In most cases, the introns are much longer than the coding regions exons.

Question 22

5´CAP

Answer 22

A residue of 7-methylguanosine linked to 5´-terminal residue of mRNA through 5´-5´-triphosphate linkage

1. protection
2. binding to ribosome

Question 23

Slicosomal introns

Answer 23

GU at 5´ end

AC at 3´-end

Question 24

Ribosomal RNA in bacteria

Answer 24

16, 23S, 5S rRNAs arising from 30S rRNA precursor

10 pseudouridine, 1 dihydrouridine, 12 methylated nucleosides

Question 25

Ribosomal RNA in eukaryote

Answer 25

45S(18S, 28S, 5,8) rRNAs

Assemly in nucleolus

Question 26

RNase

Answer 26

catalyzes the degradation of RNA into smaller components.

Question 27

half-life of mRNA eu vs pro

Answer 27

half-life mRNA shorter in pro

Question 28

what is homing

Answer 28

when DNA is introduced into a cell by parasites or other means

Question 29

Telomere

Answer 29

ends of linear eukaryotic chromosomes with tandem repeats of TG that is longer than its compliment. So 3´end has a has a region of single stranded DNA

Question 30

Telomerase

Answer 30

acts as reverse transcriptase, addidng TG to ´end

Question 31

rna dependent dna polymerase

Answer 31

an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription.